title: Pharmacokinetics of fenbendazole in dogs.
abstract: Fenbendazole was administered to dogs at a dose rate of 20 mg/kg body weight on a single occasion in gelatin capsules, on 5 consecutive days in feed, and on a single occasion as an alginate suspension. It was also administered at a dose rate of 100 mg/kg body weight on a single occasion in feed. Following single administration of 20 mg/kg fenbendazole mean maximum concentrations (Cmax) of the parent drug and its known active sulphoxide metabolite were 0.42 +/- 0.05 and 0.31 +/- 0.05 microgram/ml, respectively. Mean times until maximum concentrations were achieved (tmax) were 12.67 +/- 4.18 and 15.33 +/- 2.81 h, respectively, and areas under the plasma concentration-time curves (AUC) were 5.83 +/- 0.65 and 4.60 +/- 0.57 microgram.h/ml, respectively. Administration in feed increased the apparent bioavailability and administration for 5 consecutive days provided sustained plasma concentrations, generally greater than 0.2 microgram/ml. Administration as an alginate did not increase bioavailability or extend the persistence in plasma. It did increase the tmax to 16.80 +/- 2.93 and 20.00 +/- 2.53 h for fenbendazole and its sulphoxide metabolite, respectively. Increasing the dose from 20 mg/kg to 100 mg/kg did not substantially increase the Cmax or AUC.
authors.affiliation: Department of Veterinary Pharmacology, University of Glasgow Veterinary School, Bearsden, UK.
authors.forename: Q A
authors.initials: QA
authors.lastname: McKellar
authors.forename: P
authors.initials: P
authors.lastname: Harrison
authors.forename: E A
authors.initials: EA
authors.lastname: Galbraith
authors.forename: H
authors.initials: H
authors.lastname: Inglis
mesh_terms: D000284:Administration, Oral; D000464:Alginates; D000821:Animal Feed; D000818:Animals; D001562:Benzimidazoles / Q000097:blood; D002214:Capsules; D003692:Delayed-Action Preparations; D004285:Dogs / Q000378:metabolism*; D005273:Fenbendazole / Q000008:administration & dosage / Q000097:blood / Q000493:pharmacokinetics*; D005782:Gels
chemical_list: D000464:Alginates; D001562:Benzimidazoles; D002214:Capsules; D003692:Delayed-Action Preparations; D005782:Gels; D005273:Fenbendazole; C011030:oxfendazole